1. Technical Field
The invention refers to a driving device for a lawn trimmer with a two-stroke motor having an injection valve, a coupling, air intake and air blow-off devices and a fuel pump as well as eventual further additional aggregates.
2. Prior art
For a driving device known from EP-A-0428 186, the lawn trimmer driving gear is aligned in such a way that the crankshaft axis is placed in a straight line with the main shaft or the main pipe, thus with the drift. A fan driven by the crankshaft (fan wheel) feeds cooling air, mostly sucked below the crankcase, to the cylinder block, whereby the cooling air discharges above a separating plane lying at the level of the cylinder base over the motor unit which has lamellar type walls which should effect an appropriate air guiding with optimal cooling. This known lawn trimmer is provided with a carburetor.
Since lawn trimmers are hand-operated portable implements, a compact, light construction with a weight as low as possible, which makes an optimal cooling or air guiding difficult, is aimed at. The operativeness of the motor decisively depends on a thermally controlled air guiding.
For a chain saw known from DE-U-296 06 668, an injection installation is provided for.